1. Field of the Invention
The present invention relates to a method of manufacturing a sliding part and a compressor provided with the sliding part.
2. Description of the Prior Art
FIG. 8 is an exploded perspective view of a known shaft assembly for a compressor. The known shaft assembly includes a sliding part 110, a shaft120 and carbon-based bearings 130 and 140 which are illustrated in FIGS. 9 to 12, respectively. In FIGS. 8 and 9, the sliding part 110 is illustrated exaggeratedly on a larger scale than the remaining parts 120, 130 and 140. As shown in FIG. 9, the sliding part 110 is formed with a through-hole 111 having a flat face 112. As shown in FIG. 10, the shaft 120 includes an eccentric shaft portion 121 disposed at its one end, a flange 123 disposed at its intermediate portion and a stepped shaft portion 124 disposed at the other end. The bearing 130 includes a hub 131 having a bore 132 as shown in FIG. 11, while the bearing 140 has a bore 141 as shown in FIG. 12. The eccentric shaft portion 121 of the shaft 120 is fitted into the through-hole 111 of the sliding part 110 through engagement of a flat face 122 of the eccentric shaft portion 121 of the shaft 120 with the flat face 112 of the sliding part 110 such that the shaft 120 is axially slidable in the through-hole 111 of the sliding part 110. As shown in FIG. 8, the sliding part 110 mounted on the eccentric shaft portion 121 of the shaft 120 is rotatably received by the bore 132 of the bearing 130, while the stepped shaft portion 124 of the shaft 120 is rotatably received by the bore 141 of the bearing 140.
Since the carbon-based bearings 130 and 140 have high hardness, wear resistance is required of the sliding part 110 and the shaft 120 which are, respectively, fitted into the bores 132 and 141 of the bearings 130 and 140, so that surfaces of the sliding part 110 and the shaft 120 should have an extremely high Vickers hardness Hv of not less than 1000 as disclosed in, for example, Japanese Patent Laid-Open Publication No. 2002-98052. Since range of choice of materials and treatments for obtaining such hard surfaces is quite narrow, the sliding part 110 and the shaft 120 are quite often manufactured by employing an identical material and an identical treatment.
However, in the known shaft assembly of the above arrangement, since the flat face 122 of the eccentric shaft portion 121 of the shaft 120 and the flat face 112 of the sliding part 110, which are brought into engagement with each other, are made of the identical material and are subjected to the identical treatment and thus, have identical surface properties, thereby resulting in possible occurrence of seizing therebetween. If lubricating oil is supplied to the flat face 122 of the shaft 120 and the flat face 112 of the sliding part 110 in order to prevent such an accident, a lubricating mechanism is required to be provided additionally, so that the known shaft assembly becomes complicated structurally and thus, it becomes difficult to manufacture the known shaft assembly at low cost. Meanwhile, if one of the flat face 122 of the shaft 120 and the flat face 112 of the sliding part 110 is subjected to coating such as physical vapor deposition (PVD) so as to make surface properties of the one of the flat face 122 of the shaft 120 and the flat face 112 of the sliding part 110 different from those of the other of the flat face 122 of the shaft 120 and the flat face 112 of the sliding part 110, the coating cost rises, so that it also becomes difficult to manufacture the known shaft assembly at low cost.